The present invention relates to a pressure terminal for use with aluminum electric wire.
Aluminum electric wire has been in practical use for high-power cables and the like. On the other hand, attempts have been made to commercially utilize such aluminum electric wires for low-voltage use, but such attempts did not produce substantial results since there are difficult problems in connecting aluminum wires with terminals.
The crucial problems are as follows:
(1) Aluminum electric wire is inclined to produce an oxide film on its surface which makes the wire electrically nonconductive. Such oxide film appears from time to time even after being once eliminated. It is, therefore, necessary to remove such oxide films from surface of the wire and devise a suitable method to prevent them from reocurring. PA1 (2) If a liquid containing electrolytes intrudes between contact surfaces of the aluminum electric wire and terminal, these will be corroded due to the contact corrosion effect explained later. Therefore, a special device must be considered in order to prevent intrusion of such liquid while connecting both of the terminal and aluminum wire. PA1 (3) The aluminum conductor is more susceptible to external force than a copper conductor, and it is subject to a slight plastic deformation if such external force is prolonged on the aluminum conductor. As a result, a high pressure with which the terminal is attached to the aluminum conductor will be decreased as time elapses due to a phenomenon known as "creep." Heretofore, conventional methods overcoming the aforementioned problems have been used only in limited applications such as a high-power wiring connection, because the unit cost per connecting point has been extremely high.